/**
 * Copyright (c) 2005-2010 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: SpringContextHolder.java 1211 2010-09-10 16:20:45Z calvinxiu $
 */
package com.alter.utils.spring;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext.
 * 
 * @author calvin
 */
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

    private static ApplicationContext applicationContext = null;

    private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

    /**
     * 实现ApplicationContextAware接口, 注入Context到静态变量中.
     */
    public void setApplicationContext(ApplicationContext applicationContext) {
	logger.debug("注入ApplicationContext到SpringContextHolder:" + applicationContext);

	if (SpringContextHolder.applicationContext != null) {
	    logger.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:"
		    + SpringContextHolder.applicationContext);
	}

	SpringContextHolder.applicationContext = applicationContext; // NOSONAR
    }

    /**
     * 实现DisposableBean接口,在Context关闭时清理静态变量.
     */
    @Override
    public void destroy() throws Exception {
	SpringContextHolder.clear();
    }

    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
	assertContextInjected();
	return applicationContext;
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
	assertContextInjected();
	return (T) applicationContext.getBean(name);
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    public static <T> T getBean(Class<T> requiredType) {
	assertContextInjected();
	return applicationContext.getBean(requiredType);
    }

    /**
     * 清除SpringContextHolder中的ApplicationContext为Null.
     */
    public static void clear() {
	logger.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
	applicationContext = null;
    }

    /**
     * 检查ApplicationContext不为空.
     */
    private static void assertContextInjected() {
	if (applicationContext == null) {
	    throw new IllegalStateException("applicaitonContext未注入,请在applicationContext.xml中定义SpringContextHolder");
	}
    }
}
